Chronic toxicity in Ceriodaphnia dubia induced by graphene oxide

The unique physico-chemical properties of nanomaterials have allowed their application in different areas including electronics, energy storage, nanomedicine, environmental remediation and biotechnology. Graphene and its derivatives, in particular, have been commercially available, with prediction for increasing their production in the next years, in a way that their release into aquatic environments is very likely to occur, and the impacts of such situation on organisms are still not completely understood. In this context, we evaluated graphene oxide (GO) effects on the freshwater cladoceran Ceriodaphnia dubia through acute and chronic toxicity, feeding rates, and reactive oxygen species (ROS) generation. The mean effective concentration (EC50) estimated during acute exposure was 1.25 mg L^-1 of GO. The chronic exposure resulted in significant decrease in the number of neonates. The feeding rates were also decreased by GO exposure. Sub-lethal concentrations of GO caused an increase in ROS generation in the organisms. Our results indicated that GO cause acute and chronic effects to C. dubia. In the presence of GO there was a shift in the available energy for self-maintenance rather than feeding or reproduction activities. This study provides useful information on GO concentrations that might impair the aquatic biota, and supports regulatory efforts concerning the environmental safety of this product.